docs: def has_no_narrow_start(neuron, frac=0.9):
      '''Check if neurites have a narrow start
  
      Arguments:
          neuron(Neuron): The neuron object to test
          frac(float): Ratio that the second point must be smaller than the first
  
      Returns:
          CheckResult with a list of all first segments of neurites with a narrow start
      '''
      bad_ids = [(neurite.root_node.id, [neurite.root_node.points[1]])
                 for neurite in neuron.neurites
                 if neurite.root_node.points[1][COLS.R] < frac * neurite.root_node.points[2][COLS.R]]
      return CheckResult(len(bad_ids) == 0, bad_ids)